CARBONIFEROUS MYRIAPODA OF ILLINOIS. 423 



lar segments shown apparently upon a side view, the lower edge of the segments irreg- 

 ularly broken so that their exact proportions can hardly be told, though some of the 

 legs are partly joreserved; there is no indication, however, that the segments varied in 

 size, and all were probably about half as broad again as long. They show two features: 

 first, each segment is composed of a series of equal and similar slight transverse ridges, 

 about eight in number; these ridges are more or less tremulous or sinuous, and slightly 

 uneven, presenting faintly a beaded appearance; second, there is a lateral series, one to 

 a segment, of rather large tubercular bosses, irregularly rounded, upon the very front 

 margin of the segments. The legs are very obscure, and their jointing, as shown in the 

 figure, altogether uncertain ; as far as preserved, which may very well be not to their ex- 

 tremity, they are shorter than the breadth of the body. 



Length of fragment, 48 mm. ; apparent breadth, 5.5 mm. ; average length of segments, 

 3.6 mm.; diameter of tubercles, 1.5 mm. 



Mazon Creek, 111. Mr. R. D. Lacoe, No. 1830ab. 



Ilyodes elongata sp. nov. 

 PI. 38, fig. 2. 



The single specimen which represents this species is formed of two masses, one L- 

 shaped and overlying the other which is U-shai)ed; evidently both belonged to the same 

 individual, and their connection could have been traced had the stone been broken open 

 more favorably. The division line between the segments cannot be everywhere traced 

 from the obscurity of the preservation on the stone, but there are present evidently at 

 least one Imndred and sixty-six segments, which differed apparently not over a sixth 

 in width and that little perhaps due to a twist in the body as laid down ; they differed, 

 it would appear, as little in length, being almost uniformly about three and a half times 

 as broad as long; they show no sculpture whatever, but an obscure series of small de- 

 pressions in the middle of the segment next the suture; if the creatui-e where these so 

 appear were lying on its side, these depressions would hold precisely the position of the 

 tubercles in /. divisa and may represent the cast of weaker tubercles. 



Length of whole if extended, 65 -(-96=161 mm.; breadth, 3.5-4 mm. 



Mazon Creek, 111. Mr. R. D. Lacoe, No. 1829ab. 



Order ARCIIIPOLYPODA Scudder. 

 It is in this order that the principal additions in specific forms are to be found, and 

 they are mainly in the family Euphoberidae from which, as already stated, the genus 

 Eileticus must be removed. It is, moreover, not impossible that future discovery of 

 more perfect specimens may show that Amynilysi)es should be regarded as one of the 

 Diplopoda (allied to the Glomeridae) rathei- than as a member of the Archipolypoda; 

 but the appai'ent necessity of ventral plates of excessive width and the known armature 

 of the dorsal plates render it proper to retain it in the Archipolypoda until its structure 

 is better known, or at any rate until undoubted Diplopoda are found at so cai-ly a pe- 

 riod. 



